From: Matthew Wilcox <willy@infradead.org>
To: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
Alexander Duyck <alexander.h.duyck@linux.intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] mm/pageblock: mitigation cmpxchg false sharing in pageblock flags
Date: Sun, 16 Aug 2020 05:09:05 +0100 [thread overview]
Message-ID: <20200816040905.GF17456@casper.infradead.org> (raw)
In-Reply-To: <1597549677-7480-1-git-send-email-alex.shi@linux.alibaba.com>
On Sun, Aug 16, 2020 at 11:47:56AM +0800, Alex Shi wrote:
> +++ b/mm/page_alloc.c
> @@ -467,6 +467,8 @@ static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
> return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
> }
>
> +#define BITS_PER_CHAR 8
include/linux/bits.h:#define BITS_PER_BYTE 8
> bitmap = get_pageblock_bitmap(page, pfn);
> bitidx = pfn_to_bitidx(page, pfn);
> - word_bitidx = bitidx / BITS_PER_LONG;
> - bitidx &= (BITS_PER_LONG-1);
> + word_bitidx = bitidx / BITS_PER_CHAR;
> + bitidx &= (BITS_PER_CHAR-1);
It's not a word any more. it's a byte.
next prev parent reply other threads:[~2020-08-16 4:09 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-16 3:47 [PATCH 1/2] mm/pageblock: mitigation cmpxchg false sharing in pageblock flags Alex Shi
2020-08-16 3:47 ` [PATCH 2/2] mm/pageblock: remove false sharing in pageblock_flags Alex Shi
2020-08-16 4:17 ` Matthew Wilcox
2020-08-16 14:10 ` Alex Shi
2020-08-16 15:56 ` Alexander Duyck
2020-08-18 7:15 ` Alex Shi
2020-08-16 4:09 ` Matthew Wilcox [this message]
2020-08-16 13:53 ` [PATCH 1/2] mm/pageblock: mitigation cmpxchg false sharing in pageblock flags Alex Shi
2020-08-16 12:16 ` David Hildenbrand
2020-08-16 14:14 ` Alex Shi
2020-08-17 9:58 ` Wei Yang
2020-08-17 11:02 ` Alex Shi
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